68 



DIPTEKA. 



1. Helophilus latifrons. 



Helophilus latifrons, Loew, Centur. iv. no. 73, in Berl. ent. Zeitschr. 1863, p. 313 1 ; Osten Sacken, 

 Western Dipt., in Bull. U.S. Geol. & Geogr. Survey, iii. p. 337 2 ; Willist. Synopsis N.-Am. 

 Syrphidee, p. 188 3 . 



Hab. North America, Red River, Washington 3 , Wyoming 3 , Oregon 3 , Montana 3 , 

 Nebraska 1 , Massachusetts 3 , Connecticut 3 , Western Kansas 3 , California 2 . — Mexico, 

 Amula in Guerrero 6000 feet (H. H. Smith). 



Five specimens, which present no noteworthy difFerences from those of the United 

 States. 



2. Helophilus mexicanus. 



Helophilus mexicanus, Macq. Dipt. Exot. ii. 2, p. 64, t. 11. f . 2 1 ; Osten Sacken, Cat. Dipt. 2nd ed. 



pp. 134, 267 2 ; Willist. Synopsis N.-Am. Syrphidte, p. 186, t. 8. f. 7 3 . 

 Helophilus polygrammus, Loew, Centur. x. no. 55, in Berl. ent. Zeitschr. 1872, p. 85 4 ; Osten 



Sacken, Western Dipt., in Bull. U.S. Geol. & Geogr. Survey, iii. p. 338 \ 

 Asemosyrphus bicolor, Bigor, Ann. Soc. Ent. Fr. 1883, p. 350 °. 

 Asemosyrphus oculiferus, Bigot, loc. cit. p. 350 1 . 

 Asemosyrphus flavicaudatus, Bigot, loc. cit. p. 351 s . 

 Asemosyrphus nigroscutatus, Bigot, loc. cit. p. 351 s . 



Hab. United States, Washington 3 , California 3 4 5 7 . — Mexico 1 2 6 7 8 , Omilteme 

 8000 feet, Chilpancingo 4600 feet, Xucumanatlan 7000 feet, Tepetlapa 3000 feet, 

 all in Guerrero (//. H. Smith), Jalisco (Schumann), Mexico city (F. I). Godman), 

 Orizaha (II. H. Smith and F. I). Godman). 



Thirty-seven specimens. These show colorational variations, and it is hard to say 

 whether the differences are of varietal or specific value. ln length they vary from 

 seven to nearly twelve millim. In the shape and colour of the head there are no 

 appreciable differences. 



Seven specimens, including both sexes, from Mexico city and Jalisco, have the meso- 

 notum of a distinctly olivaceous-greenish appearance, with a metallic lustre, and the 

 pile wholly yellow. The remainder, from Mexico city, Jalisco, and the other places 

 mentioned, have the mesonotum opaque cinereous, without apparent metallic or 

 greenish lustre ; in all, the oblique line on the outer posterior part may be wanting. 

 The three males of the first-mentioned variety have the abdomen red, with the first 

 segment, and a triangular spot on the second, black, the fourth segment with a lunule ; 

 these specimens must be very similar to those described by Bigot under the name of 

 Asemosyrphus Ucolor. The remaining males, eleven, with opaque mesonotum, are all 

 nearly uniform in length (about seven millim.), and agree in having the second abdo- 

 minal segment opaque black, with two grey lunules ; the third segment with the 

 posterior and lateral margins broadly red, leaving an oval, opaque, black portion, upon 

 which partly rest two much curved grey lunules ; the fourth segment with two small 



